Phase change ink imaging component with MICA-type silicate layer

ABSTRACT

An offset printing apparatus having a coated imaging member for use with phase-change inks, has a substrate, an optional intermediate layer, and thereover an outer coating with a mica-type silicate material, and an optional heating member associated with the offset printing apparatus.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] Reference is made to the following commonly assigned, copendingpatent applications, including U.S. patent application Ser. No. ______(D/A1022), filed ______, entitled, “Phase Change Ink Imaging ComponentHaving Elastomer Outer Layer;” U.S. patent application Ser. No. ______(D/A1022Q), filed ______, entitled, “Phase Change Ink Imaging Componentwith Outer Layer Having Haloelastomer with Pendant Chains;” U.S. patentapplication Ser. No. ______ (D/A1022Q1), filed ______, entitled, “PhaseChange Ink Imaging Component with Thermoplastic Layer;” U.S. patentapplication Ser. No. ______ (D/A1022Q2), filed ______, entitled, “PhaseChange Ink Imaging Component with Thermoset Layer;” U.S. patentapplication Ser. No. ______ (D/A1022Q3), filed ______, entitled, “PhaseChange Ink Imaging Component with Fluorosilicone Layer;” U.S. patentapplication Ser. No. ______ (D/A1022Q4), filed ______, entitled, “PhaseChange Ink Imaging Component with Latex Fluoroelastomer Layer;” U.S.patent application Ser. No. ______ (D/A1022Q6), filed ______, entitled,“Phase Change Ink Imaging Component with Q-Resin Layer;” U.S. patentapplication Ser. No. ______ (D/A1022Q7), filed ______, entitled, “PhaseChange Ink Imaging Component with Polymer Blend Layer;” and U.S. patentapplication Ser. No. ______ (D/A1022Q8), filed ______, entitled, “PhaseChange Ink Imaging Component with Polymer Hybrid Layer.” The disclosuresof each of these patent applications is hereby incorporated by referencein their entirety.

BACKGROUND OF THE INVENTION

[0002] The present invention relates generally to an imaging apparatusand layers for components thereof, and for use in offset printing or inkjet printing apparatuses. The layers herein are useful for many purposesincluding layers for transfer components, including transfix ortransfuse components, imaging components, and like components. Morespecifically, the present invention relates to layers comprising asilicate material, such as a mica-type silicate material. The layers ofthe present invention may be useful in components used in combinationwith ink or dye materials. In embodiments, the layers can be used incombination with phase change inks such as solid inks.

[0003] Ink jet printing systems using intermediate transfer, transfix ortransfuse members are well known, such as that described in U.S. Pat.No. 4,538,156. Generally, the printing or imaging member is employed incombination with a printhead. A final receiving surface or print mediumis brought into contact with the imaging surface after the image hasbeen placed thereon by the nozzles of the printhead. The image is thentransferred and fixed to a final receiving surface.

[0004] More specifically, the phase-change ink imaging process begins byfirst applying a thin liquid, such as, for example, silicone oil, to animaging member surface. The solid or hot melt ink is placed into aheated reservoir where it is maintained in a liquid state. This highlyengineered ink is formulated to meet a number of constraints, includinglow viscosity at jetting temperatures, specific visco-elastic propertiesat component-to-media transfer temperatures, and high durability at roomtemperatures. Once within the printhead, the liquid ink flows throughmanifolds to be ejected from microscopic orifices through use ofproprietary piezoelectric transducer (PZT) printhead technology. Theduration and amplitude of the electrical pulse applied to the PZT isvery accurately controlled so that a repeatable and precise pressurepulse can be applied to the ink, resulting in the proper volume,velocity and trajectory of the droplet. Several rows of jets, forexample four rows, can be used, each one with a different color. Theindividual droplets of ink are jetted onto the liquid layer on theimaging member. The imaging member and liquid layer are held at aspecified temperature such that the ink hardens to a ductilevisco-elastic state.

[0005] After depositing the image, a print medium is heated by feedingit through a preheater and into a nip formed between the imaging memberand a pressure member, either or both of which can also be heated. Ahigh durometer synthetic pressure member is placed against the imagingmember in order to develop a high-pressure nip. As the imaging memberrotates, the heated print medium is pulled through the nip and ispressed against the deposited ink image with the help of a pressuremember, thereby transferring the ink to the print medium. The pressuremember compresses the print medium and ink together, spreads the inkdroplets, and fuses the ink droplets to the print medium. Heat from thepreheated print medium heats the ink in the nip, making the inksufficiently soft and tacky to adhere to the print medium. When theprint medium leaves the nip, stripper fingers or other like members,peel it from the printer member and direct it into a media exit path.

[0006] To optimize image resolution, the transferred ink drops shouldspread out to cover a predetermined area, but not so much that imageresolution is compromised or lost. The ink drops should not melt duringthe transfer process. To optimize printed image durability, the inkdrops should be pressed into the paper with sufficient pressure toprevent their inadvertent removal by abrasion. Finally, image transferconditions should be such that nearly all the ink drops are transferredfrom the imaging member to the print medium. Therefore, it is desirablethat the imaging member has the ability to transfer the image to themedia sufficiently.

[0007] The imaging member is multi-functional. First, the ink jetprinthead prints images on the imaging member, and thus, it is animaging member. Second, after the images are printed on the imagingmember, they can then transfixed or transfused to a final print medium.Therefore, the imaging member provides a transfix or transfuse function,in addition to an imaging function.

[0008] In order to ensure proper transfer and fusing of the ink off theimaging member to the print medium, certain nip temperature, pressureand compliance are required. Unlike laser printer imaging technology inwhich solid fills are produced by sheets of toner, the solid ink isplaced on the imaging member one pixel at a time and the individualpixels must be spread out during the transfix process to achieve auniform solid fill. Also, the secondary color pixels on the imagingmember are physically taller than the primary color pixels because thesecondary pixels are produced from two primary pixels. Therefore,compliance in the nip is required to conform around the secondary pixelsand to allow the primary pixel neighbors to touch the media with enoughpressure to spread and transfer. The correct amount of temperature,pressure and compliance is required to produce acceptable image quality.

[0009] Currently, the imaging member useful for solid inks or phasechange inks comprises anodized aluminum. This member operates at about57° C. to about 64° C. and can be used with a heater that preheats theprint media prior to entering the nip. Otherwise, the imaging member mayinclude a heater associated therewith. The heater may be associatedanywhere on the offset printing apparatus. The current aluminum-imagingmember has several drawbacks. A high nip load of up to about 770 poundsis needed for transfix or transfuse operations. Further, because of thehigh nip load, bulky mechanisms and supporting structures are needed,resulting in increased printer weight and cost. One example is that afairly complex two-layer pressure roller is needed. In addition, thefirst copy out time is unacceptable because of the bulky weight.Moreover, low cohesive failure temperature is another drawback to use ofan anodized aluminum drum.

[0010] Several coatings for the imaging member have been suggested.Examples are listed below.

[0011] U.S. Pat. No. 5,092,235 discloses a pressure fixing apparatus forink jet inks having 1) outer shell of rigid, non-compliant material suchas steel, or polymer such as acetal homopolymer or Nylon 6/6 and 2) anunderlayer of elastomer material having a hardness of about 30 to 60, orabout 50 to 60.

[0012] U.S. Pat. No. 5,195,430 discloses a pressure fixing apparatus forink jet inks having 1) outer shell of rigid, non-compliant material suchas steel, or polymer such as acetal homopolymer or Nylon 6/6 and 2) anunderlayer of elastomer material having a hardness of about 30 to 60, orabout 50 to 60, which can be polyurethane (VIBRATHANE, orREN:C:O-thane).

[0013] U.S. Pat. No. 5,389,958 discloses an intermediate transfermember/image receiving member having a surface of metal (aluminum,nickel, iron phosphate), elastomers (fluoroelastomers,perfluoroelastomers, silicone rubber, polybutadiene), plastics(polyphenylene sulfide), thermoplastics (polyethylene, polyamide(nylon), FEP), thermosets (metals, ceramics), and a pressure roller withelastomer surface.

[0014] U.S. Pat. No. 5,455,604 discloses a fixing mechanism and pressurewheels, wherein the pressure wheels can be comprised of a steel orplastic material such as DELRIN. Image-receiving drum 40 can be a rigidmaterial such as aluminum or stainless steel with a thin shell mountedto the shaft, or plastic.

[0015] U.S. Pat. No. 5,502,476 teaches a pressure roller having ametallic core with elastomer coating such as silicones, urethanes,nitriles, or EPDM, and an intermediate transfer member surface ofliquid, which can be water, fluorinated oils, glycol, surfactants,mineral oil, silicone oil, functional oils such as mercapto siliconeoils or fluorinated silicone oils or the like, or combinations thereof.

[0016] U.S. Pat. No. 5,614,933 discloses an intermediate transfermember/image receiving member having a surface of metal (aluminum,nickel, iron phosphate), elastomers (fluoroelastomers,perfluoroelastomers, silicone rubber, polybutadiene), plastics(polyphenylene sulfide), thermoplastics (polyethylene, polyamide(nylon), FEP), thermosets (metals, ceramics), or polyphenylene sulfideloaded with PTFE, and a pressure roller with elastomer surface.

[0017] U.S. Pat. No. 5,790,160 discloses an intermediate transfermember/image receiving member having a surface of metal (aluminum,nickel, iron phosphate), elastomers (fluoroelastomers,perfluoroelastomers, silicone rubber, polybutadiene), plastics(polyphenylene sulfide), thermoplastics (polyethylene, polyamide(nylon), FEP), thermosets (metals, ceramics), or polyphenylene sulfideloaded with PTFE, and a pressure roller with elastomer surface.

[0018] U.S. Pat. No. 5,805,191 an intermediate transfer member/imagereceiving member having a surface of metal (aluminum, nickel, ironphosphate), elastomers (fluoroelastomers, perfluoroelastomers, siliconerubber, polybutadiene), plastics (polyphenylene sulfide), thermoplastics(polyethylene, polyamide (nylon), FEP), thermosets (metals, ceramics),or polyphenylene sulfide loaded with PTFE, and an outer liquid layer ofliquid, which can be water, fluorinated oils, glycol, surfactants,mineral oil, silicone oil, functional oils such as mercapto siliconeoils or fluorinated silicone oils or the like, or combinations thereof.

[0019] U.S. Pat. No. 5,808,645 discloses a transfer roller having ametallic core with elastomer covering of silicone, urethanes, nitrites,and EPDM.

[0020] U.S. Pat. No. 6,196,675 B1 discloses separate image transfer andfusing stations, wherein the fuser roller coatings can be silicones,urethanes, nitrites and EPDM.

[0021] U.S. Pat. No. 5,777,650 discloses a pressure roller having anelastomer sleeve, and an outer coating that can be metals, (aluminum,nickel, iron phosphate), elastomers (fluoroelastomers,perfluoroelastomers, silicone rubber, polybutadiene), plastics(polyphenylene sulfide with PTFE filler), thermoplastics (polyethylene,polyamide (nylon), FEP), thermosets (acetals, ceramics). Preferred isannodized aluminum.

[0022] In addition, many different types of outer coatings for transfermembers, fuser members, and intermediate transfer members have been usedin the electrostatographic arts using powder toner, but not with liquidinks or phase change inks. Several examples are listed herein.

[0023] U.S. Pat. No. 5,361,126 discloses an imaging apparatus includinga transfer member including a heater and pressure-applying roller,wherein the transfer member includes a fabric substrate and animpurity-absorbent material as a top layer. The impurity-absorbingmaterial can include a rubber elastomer material.

[0024] U.S. Pat. No. 5,337,129 discloses an intermediate transfercomponent comprising a substrate and a ceramer or grafted ceramercoating comprised of integral, interpenetrating networks ofhaloelastomer, silicon oxide, and optionally polyorganosiloxane.

[0025] U.S. Pat. Nos. 5,340,679 discloses an intermediate transfercomponent comprised of a substrate and thereover a coating comprised ofa volume grafted elastomer, which is a substantially uniform integralinterpenetrating network of a hybrid composition of a fluoroelastomerand a polyorganosiloxane.

[0026] U.S. Pat. No. 5,480,938 describes a low surface energy materialcomprising a volume grafted elastomer which is a substantially uniformintegral interpenetrating network of a hybrid composition of afluoroelastomer and a polyorganosiloxane, the volume graft having beenformed by dehydrofluorination of fluoroelastomer by a nucleophilicdehydrofluorinating agent, followed by a hydrosilation reaction,addition of a hydrogen functionally terminated polyorganosiloxane and ahydrosilation reaction catalyst.

[0027] U.S. Pat. No. 5,366,772 describes a fuser member comprising asupporting substrate, and a outer layer comprised of an integralinterpenetrating hybrid polymeric network comprised of a haloelastomer,a coupling agent, a functional polyorganosiloxane and a crosslinkingagent.

[0028] U.S. Pat. No. 5,456,987 discloses an intermediate transfercomponent comprising a substrate and a titamer or grafted titamercoating comprised of integral, interpenetrating networks ofhaloelastomer, titanium dioxide, and optionally polyorganosiloxane.

[0029] U.S. Pat. No. 5,848,327 discloses an electrode member positionednear the donor member used in hybrid scavengeless development, whereinthe electrode members have a composite haloelastomer coating.

[0030] U.S. Pat. No. 5,576,818 discloses an intermediate toner transfercomponent including: (a) an electrically conductive substrate; (b) aconformable and electrically resistive layer comprised of a firstpolymeric material; and (c) a toner release layer comprised of a secondpolymeric material selected from the group consisting of afluorosilicone and a substantially uniform integral interpenetratingnetwork of a hybrid composition of a fluoroelastomer and apolyorganosiloxane, wherein the resistive layer is disposed between thesubstrate and the release layer.

[0031] U.S. Pat. No. 6,035,780 discloses a process for forming a layeron a component of an electrostatographic apparatus, including mixing afirst fluoroelastomer and a polymeric siloxane containing free radicalreactive functional groups, and forming a second mixture of theresulting product with a mixture of a second fluoroelastomer and asecond polysiloxane compound.

[0032] U.S. Pat. No. 5,537,194 discloses an intermediate toner transfermember comprising: (a) a substrate; and (b) an outer layer comprised ofa haloelastomer having pendant hydrocarbon chains covalently bonded tothe backbone of the haloelastomer.

[0033] U.S. Pat. No. 5,753,307 discloses fluoroelastomer surfaces and amethod for providing a fluoroelastomer surface on a supporting substratewhich includes dissolving a fluoroelastomer; adding adehydrofluorinating agent; adding an amino silane to form a resultinghomogeneous fluoroelastomer solution; and subsequently providing atleast one layer of the homogeneous fluoroelastomer solution to thesupporting substrate.

[0034] U.S. Pat. No. 5,840,796 describes polymer nanocompositesincluding a mica-type layered silicate and a fluoroelastomer, whereinthe nanocomposite has a structure selected from the group consisting ofan exfoliated structure and an intercalated structure.

[0035] U.S. Pat. No. 5,846,643 describes a fuser member for use in anelectrostatographic printing machine, wherein the fuser member has atleast one layer of an elastomer composition comprising a siliconeelastomer and a mica-type layered silicate, the silicone elastomer andmica-type layered silicate form a delaminated nanocomposite withsilicone elastomer inserted among the delaminated layers of themica-type layered silicate.

[0036] It is desired to provide a multi-functional imaging member foruse with phase change ink printing machines, which has the ability toreceive an image, and either transfer, or transfer and fuse the image toa print medium. It is desired that the imaging member when having heatassociated therewith, be thermally stable for conduction for fusing orfixing. It is further desired that the imaging member have a relativelylow nip load, in order to decrease the weight and cost of the printingmachine, and in order to provide an acceptable first copy out time.

SUMMARY OF THE INVENTION

[0037] The present invention provides, in embodiments: an offsetprinting apparatus for transferring a phase change ink onto a printmedium comprising: a) a phase change ink component for applying a phasechange ink in a phase change ink image; b) an imaging member foraccepting the phase change ink image from the phase change inkcomponent, and transferring the phase change ink image from the imagingmember to the print medium, the imaging member comprising: i) an imagingsubstrate, and thereover ii) an outer coating comprising a mica-typesilicate material.

[0038] The present invention further provides, in embodiments: an offsetprinting apparatus for printing a phase change ink onto a print mediumcomprising: a) a phase change ink component for applying a phase changeink in a phase change ink image; b) an imaging member for accepting saidphase change ink image from said phase change ink component, andtransferring the phase change ink image from said imaging member to saidprint medium and for fixing the phase change ink image to said printmedium, the imaging member comprising in order: i) an imaging substrate,ii) an intermediate layer, and iii) an outer coating comprising amica-type silicate material; and c) a heating member associated with theoffset printing apparatus.

[0039] In addition, the present invention provides, in embodiments: anoffset printing apparatus comprising a phase change ink componentcontaining a phase change ink; an imaging member comprising a substrate,and thereover an outer coating comprising a mica-type silicate material;and a heating member associated with the offset printing apparatus,wherein the phase change ink component dispenses the phase change inkonto the imaging member, and wherein the phase change ink is solid atroom temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above embodiments of the present invention will becomeapparent as the following description proceeds upon reference to thedrawings, which include the following figures:

[0041]FIG. 1 is an illustration of an embodiment of the invention, andincludes a transfer printing apparatus using an imaging member in theform of a drum.

[0042]FIG. 2 is an enlarged view of an embodiment of a printing drumhaving a substrate and an outer mica-type silicate layer thereon.

[0043]FIG. 3 is an enlarged view of an embodiment of a printing drumhaving a substrate, an optional intermediate layer, and an outermica-type silicate layer thereon.

[0044]FIG. 4 is a schematic view of the process for forming a mica-typelayered silicate and silicone elastomer nanocomposite.

[0045]FIG. 5 is a graph of weight toluene versus volume fraction ofnanocomposite.

DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention is directed to an offset printing apparatususeful with phase-change inks such as solid inks, and comprising acoated imaging member capable of accepting, transferring and in someembodiments, fixing an ink image to a print medium. The imaging membercan be a roller such as a drum, or a film component such as a film,sheet, belt or the like. In embodiments, the imaging member comprises asubstrate and an outer layer comprising a mica-type silicate material.In an alternative embodiment, the imaging member comprises a substrate,an optional intermediate layer, and outer layer comprising a mica-typesilicate material. The substrate, intermediate layer, and/or outer layercan further comprise fillers dispersed or contained therein.

[0047] The details of embodiments of phase-change ink printing processesare described in the patents referred to above, such as U.S. Pat. Nos.5,502,476; 5,389,958; and 6,196,675 B1, the disclosures of each of whichare hereby incorporated by reference in their entirety.

[0048] Referring to FIG. 1, offset printing apparatus 1 is demonstratedto show transfer of an ink image from the imaging member to a finalprinting medium or receiving substrate. As the imaging member 3 turns inthe direction of arrow 5, a liquid surface 2 is deposited on imagingmember 3. The imaging member 3 is depicted in this embodiment as a drummember. However, it should be understood that other embodiments can beused, such as a belt member, film member, sheet member, or the like. Theliquid layer 2 is deposited by an applicator 4 that may be positioned atany place, as long as the applicator 4 has the ability to make contactand apply liquid surface 2 to imaging member 3.

[0049] The ink used in the printing process can be a phase change ink,such as, for example, a solid ink. The term “phase change ink” meansthat the ink can change phases, such as a solid ink becoming liquid inkor changing from solid into a more malleable state. Specifically, inembodiments, the ink can be in solid form initially, and then can bechanged to a molten state by the application of heat energy. The solidink may be solid at room temperature, or at about 25° C. The solid inkmay possess the ability to melt at relatively high temperatures abovefrom about 85° C. to about 150° C. The ink is melted at a hightemperature and then the melted ink 6 is ejected from printhead 7 ontothe liquid layer 2 of imaging member 3. The ink is then cooled to anintermediate temperature of from about 20° C. to about 80° C., or about72° C., and solidifies into a malleable state in which it can then betransferred onto a final receiving substrate 8 or print medium 8.

[0050] The ink has a viscosity of from about 5 to about 30 centipoise,or from about 8 to about 20 centipoise, or from about 10 to about 15centipoise at about 140° C. The surface tension of suitable inks is fromabout 23 to about 50 dynes/cm. Examples of a suitable inks for useherein include those described in U.S. Pat. No. 4,889,560; 5,919,839;6,174,937; and 6,309,453, the disclosure each of which are herebyincorporated by reference in their entirety.

[0051] Some of the liquid layer 2 is transferred to the print medium 8along with the ink. A typical thickness of transferred liquid is about100 angstroms to about 100 nanometer, or from about 0.1 to about 200milligrams, or from about 0.5 to about 50 milligrams, or from about 1 toabout 10 milligrams per print medium.

[0052] Suitable liquids that may be used as the print liquid surface 2include water, fluorinated oils, glycol, surfactants, mineral oil,silicone oil, functional oils, and the like, and mixtures thereof.Functional liquids include silicone oils or polydimethylsiloxane oilshaving mercapto, fluoro, hydride, hydroxy, and the like functionality.

[0053] Feed guide(s) 10 and 13 help to feed the print medium 8, such aspaper, transparency or the like, into the nip 9 formed between thepressure member 11 (shown as a roller), and imaging member 3. It shouldbe understood that the pressure member can be in the form of a belt,film, sheet, or other form. In embodiments, the print medium 8 is heatedprior to entering the nip 9 by heated feed guide 13. When the printmedium 8 is passed between the printing medium 3 and the pressure member11, the melted ink 6 now in a malleable state is transferred from theimaging member 3 onto the print medium 8 in image configuration. Thefinal ink image 12 is spread, flattened, adhered, and fused or fixed tothe final print medium 8 as the print medium moves between nip 9.Alternatively, there may be an additional or alternative heater orheaters (not shown) positioned in association with offset printingapparatus 1. In another embodiment, there may be a separate optionalfusing station located upstream or downstream of the feed guides.

[0054] The pressure exerted at the nip 9 is from about 10 to about 1,000psi., or about 500 psi, or from about 200 to about 500 psi. This isapproximately twice the ink yield strength of about 250 psi at 50° C. Inembodiments, higher temperatures, such as from about 72 to about 75° C.can be used, and at the higher temperatures, the ink is softer. Once theink is transferred to the final print medium 8, it is cooled to anambient temperature of from about 20° C. to about 25° C.

[0055] Stripper fingers (not shown) may be used to assist in removingthe print medium 8 having the ink image 12 formed thereon to a finalreceiving tray (also not shown).

[0056]FIG. 2 demonstrates an embodiment of the invention, whereinimaging member 3 comprises substrate 15, having thereover outer coating16.

[0057]FIG. 3 depicts another embodiment of the invention. FIG. 3 depictsa three-layer configuration comprising a substrate 15, intermediatelayer 17 positioned on the substrate 15, and outer layer 16 positionedon the intermediate layer 17. In embodiments, an outer liquid layer 2(as described above) may be present on the outer layer 16.

[0058] In embodiments, the outer release layer 16 comprises a mica-typesilicate material. In embodiments, the outer release layer comprises asilicone elastomer and mica-type layered silicate material. In anotherembodiment, the silicone elastomer and mica-type layered silicate form adelaminated nanocomposite. In a further embodiment, the mica-typelayered silicate has a high aspect ratio structure. In yet anotherembodiment, the silicone elastomer is formed by curing apolyorganosiloxane. An example of a polyorganosiloxane is one having thefollowing formula:

[0059] where R is hydrogen or substituted or unsubstituted alkyl,alkoxy, or alkenyl having from about 1 to about 20 carbon atoms, or fromabout 2 to about 10 carbon atoms, or aryl having from about 4 to about12 carbon atoms, or from about 6 to about 10 carbon atoms; and whereeach of A and B may be any of alkyl or alkoxy having from about 1 toabout 20 carbon atoms, or from about 2 to about 10 carbon atoms,hydroxy, or vinyl groups; and 0<m/n<about 1, and m+n>about 350.

[0060] By way of example, A, B and R can be the same or different, andcan be alkyl groups including alkoxy and substituted alkoxy. Specificexamples include chloropropyl, trifluoropropyl, mercaptopropyl,carboxypropyl, aminopropyl, cyanopropyl and the like, and substitutedalkoxy substituents such as glycidoxypropyl, methacryloxypropyl, and thelike. Typical alkenyl substituents include vinyl, propenyl, and thelike, while substituted alkenyl include halogen-substituted materialssuch as chlorovinyl, bromopropenyl, and the like. Typical aryl orsubstituted aryl groups include phenyl, chlorophenyl, bromophenyl, andthe like. Hydrogen, hydroxy, ethoxy and vinyl are specific examples forA, B and/or R, and allow for superior crosslinkability. Methyl,trifluoropropyl and phenyl are examples of substituents for A, B and/orR in providing superior solvent and oil resistance, higher temperaturestability, and surface lubricity.

[0061] The ratio of m/n as between 0 and 1, identifies thepolyorganosiloxane as a copolymer. Similarly, the sum of m+n beinggreater than 350, identifies it as an elastomeric material.

[0062] Other examples of polyorganosiloxanes include condensationcurable polyorganosiloxanes, such as silanol-terminatedpolydimethylsiloxanes. Examples include those having the followingformula:

[0063] where n′ is an integer of from about 350 to about 2700, or fromabout 500 to about 1500.

[0064] The terminating silanol groups render the materials susceptibleto condensation under acid or mild basic conditions. These groups areproduced by kinetically controlled hydrolysis of chlorosilanes. Roomtemperature vulcanizable (RTV's) systems are formulated from thesesilanol-terminated polymers with a molecular weight of from about 26,000to about 200,000. These silanol-terminated polymers may be crosslinkedwith small quantities of multifunctional silanes, which condense withthe silanol group.

[0065] Suitable crosslinking agents for condensation curedpolyorganosiloxanes include esters of orthosilicic acid, esters ofpolysilic acid, and alkyl trialkoxy silanes. Specific examples ofsuitable crosslinking agents for the condensation cured materialsinclude tetramethylorthosilicate, tetraethylorthosilicate,2-methoxyethylsilicate, tetrahydrofurfurylsilicate, ethylpolysilicate,butylpolysilicate, and the like crosslinking agents. During thecrosslinking reaction, an alcohol is typically split out leading to acrosslinked network. Condensed tetraethylorthosilicate is a specificexample of a crosslinking agent.

[0066] A sufficient amount of crosslinking agent is needed to completelycrosslink the active end groups on the disilanol polymer. The amount ofcrosslinking agent required depends on the number average molecularweight of the disilanol polymer employed. With higher average molecularweight polymers, fewer active end groups are present and thus a lesseramount of crosslinking agent is required, and the opposite is true forlower average molecular weight polymers. Generally, with alpha omegahydroxy polydimethyl siloxane having a number average molecular weightof between about 26,000 to about 100,000, from about 1 to about 20 partsby weight, or from about 2.5 to about 10 parts by weight of condensedtetraethylorthosilicate per 100 parts by weight of disilanol polymer canbe used.

[0067] In another embodiment, a liquid addition-cured polyorganosiloxaneis achieved by using siloxanes containing vinyl groups at the chain endsand/or scattered randomly along the chain, along with siloxanes havingtwo or more silicon hydrogen bonds per molecule. Typically thesematerials are cured at temperatures of from about 100° C. to about 250°C.

[0068] Typical addition-cured polyorganosiloxane materials arerepresented by the formula:

[0069] wherein s and r are integers and 0<s/r<about 1, about350<r+s<about 2700. In the above formula, A″ and B″ can be the same ordifferent and examples include hydroxy, alkoxy such as methoxy, ethoxy,propoxy, and the like, hydride, vinyl, amine and the like. R″ can bealkyl such as methyl, ethyl, propyl, butyl and the like, substitutedalkyl such as chloropropyl, fluoropropyl, trifluoropropyl, and the like,phenyl, and vinyl.

[0070] For each molecule of the above formula, there can be at least atotal of 2 vinyl groups in the A″, B″ and any of the several R″ siteswithin the formula. In the presence of suitable catalysts such assolutions- or complexes of chloroplatinic acid or other platinumcompounds in alcohols, ethers or divinylsiloxane, reaction occurs withtemperatures of from about 100° C. to about 250° C. with the addition ofpolyfunctional silicon hydride to the unsaturated groups in thepolysiloxane chain. Elastomers produced in this manner exhibit increasedtoughness, tensile strength and dimensional stability. Typically, thesematerials comprise the addition of two separate parts of theformulation, part A and part B, wherein part A contains the vinylterminated polyorganosiloxane, the catalyst and the filler; and wherepart B contains the same or another vinyl-terminated polyorganosiloxane,the crosslinking moiety such as a hydride functional silane and the sameor additional filler. Part A and part B are normally in a ratio of 1to 1. During the additional curing operation the material is crosslinkedvia the equation:

≡SiH+CH₂═CHSi≡SiCH₂CH₂Si═

[0071] Because hydrogen is added across the double bond, no labilebyproduct such as acids or alcohols is obtained.

[0072] Crosslinking catalysts are well-known in the art and include forthe condensation cured polyorganosiloxanes, among others, stannousoctoate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltindicaproate, and the like.

[0073] A nanocomposite as used herein refers to nanoscale fillers in apolymer, an example being a mica-type layered silicate. A specificexample is a mica-type layered silicate in an intercalated or exfoliatedstate in a polymer.

[0074] The term “delaminated” (also referred to herein as exfoliated)refers to the host layers (having a thickness on a nanometer scale)being dispersed in a continuous polymer matrix.

[0075] The term “aspect ratio” shall refer to the ratio of the length tothickness of the mica-type layer silicates, and the term “high aspectratio” shall define a large dimensional ratio of the mica-type layeredsilicate (MTS).

[0076] In embodiments, the mica-type layered silicate has a particlesize having a maximum length of from about 1 to about 10 micrometers, orfrom about 3 to about 5 micrometers.

[0077] The term “mica-type layered silicate” refers to a leaf orsheet-like laminated phyllosilicate mineral, typically natural orsynthetic complex hydrous silicates based on aluminum, magnesium,sodium, potassium, calcium, lithium, iron, and like silicates, havingflat, six-sided monoclinic crystals, low hardness, and perfect ornear-perfect basal cleavage. Typically, mica-type layered silicates havea high degree of flexibility, elasticity and toughness, and have laminasof on the order of about 10 angstroms in thickness, or from about 1 toabout 20 angstroms, which under mild shear can be delaminated orexfoliated. Typical examples include the principle mica-types of thegeneral formula:

W₂(X,Y)₄₋₆Z₈O₂₀(OH,F)₄

[0078] where W can be potassium or the like; X, Y are aluminum,magnesium, iron or lithium; and Z is silicon, aluminum, or both siliconand aluminum. In certain clay compositions some of the Z atoms can besilicon and the remaining Z atoms can be aluminum. Examples of mica-typesilicates include muscovite, phlogopite, biotite, lepidolite,montmorillonite, bentonite, hectorite, vermiculite and saponite. Theformula given above is by necessity only approximate, since mica-typesilicates (MTS) are minerals having various impurities. Commerciallyavailable materials include montmorillonite, bentonite and hectoritewhich are available from Southern Clay Products, Gonzales Texas. A listof suitable mica-type silicates can be found in the CRC Handbook ofChemistry and Physics 58th Edition, 1977-8, pp. B-250 to B-252, or inthe 77th Edition, pp. 4-137 to 4-147, the disclosures of which arehereby incorporated herein by reference in their entirety.

[0079] Two types of nanocomposites representing the end members of astructural hierarchy are possible: (a) intercalated, in which extendedpolymer chains are intercalated between the host layers resulting in awell-ordered multilayer, where the layers of the silicate retain theirstructural registry; and (b) delaminated (also referred herein asexfoliated), in which the host layers having a thickness on a nanometerscale, are dispersed in a continuous polymer matrix. In contrast to theintercalated hybrids, the interlayer expansion in delaminatednanocomposites is comparable to the radius of gyration of the polymer,and the host layers have lost their structural registry.

[0080] As previously mentioned, the mica-type layered silicate haslaminas on the order of about 10 angstroms in thickness. The layeredsilicate also has a large length to thickness ratio because of theplate-like structure, which has a high aspect ratio. Typically themica-type layered silicates have a maximum length on the order of about1 micrometer, and an aspect ratio of length to thickness of from about100 to about 1000. As a result, the mica-type layered silicates whenused as a filler to enhance the thermal conductivity or modulus of thesilicone elastomer, form a continuous touching path to conduct heat.

[0081] It is believed that the sheets of the mica-type layered silicateprovide antioxidant properties due to their large surface area whichthermally stabilizes the area that surrounds it. Further, the mica-typelayered silicates provide a large surface area barrier to releaseagents, thereby resulting in reduction of swelling of the siliconeelastomer.

[0082] The outer layer may be prepared by mixing with mechanical shear,a silicone elastomer, such as a polyorganosiloxane, with a mica-typelayered silicate to delaminate the layers of the mica-type layeredsilicate and to disperse the delaminated layers of the mica-type layeredsilicate in the silicone elastomer. A crosslinking agent and catalystare added in amounts sufficient to provide crosslinking of the siliconeelastomer. The silicone elastomer delaminated nanocomposite is shapedinto a layer, placed on the phase change ink imaging member, and cured.

[0083] More specifically, attention is directed now to FIG. 4, whereinthe manufacture of thermally-stable, swell-resistant elastomercompositions is schematically illustrated. In this schematic, the firstarea 100 illustrates the laminated mica-type layered silicates 102 in apolyorganosiloxane monomer 104. When the mica-type layered silicates 102are subjected to mechanical shear, the layers delaminate or exfoliatesuch that the polyorganosiloxane monomer 104 and individual layers ofthe mica-type layered silicate 102 are relatively uniformly mixed. Thisis illustrated in the second area 106 of the Figure. Upon the additionof suitable amounts of crosslinking agent and catalyst, and followingthe desired shaping, a delaminated nanocomposite is formed. Shaping canbe accomplished by flow coating, slot coating, dipping or spraying ontoa substrate surface such as a roll. Shaping can also be accomplished bymolding in the form of a roll and curing the shaped silicone elastomercomposition to provide a silicone elastomer filled with a mica-typelayered silicate. The silicone elastomer filled with mica-type layeredsilicate is illustrated in the third area 108 of the FIG. 4 with thedelaminated layers of the mica-type layered silicate 102 dispersed amongthe silicone elastomer 110.

[0084] The delaminating phenomenon starts with surface treating themica-type layered silicate with long chain alkyl ammonium salts or aminoacids such as dimethyl dioctadecyl ammonium salt or n-dodecylamino acid.Surface treating provides the mica-type silicate with an organophilicnature. This will then enhance the wetting of the mica-type layeredsilicate by silicone materials. On mixing the surface treated mica-typelayered silicate with silicone, the silicone penetrates the mica-typelayered silicate lamellae causing each lamella to be surrounded bysilicone as the mica-type silicate exfoliates.

[0085] Experiments to conduct swelling evaluations of the presentsilicone elastomer compositions have shown that the presence of onlyabout 5 percent by weight in the elastomer composition of the mica-typelayered silicates, when made into a silicone elastomer and subjected toswelling in the presence of polydimethylsiloxane oil, resulted in areduction in swelling of about 50 percent. That is, the amount of swellwas reduced by one-half with the presence of only about 5 percent byweight of the mica-type layered silicate.

[0086]FIG. 5 is a graphical representation of the reduction in massuptake as expressed as weight of toluene uptake in the illustratedvolume fractions of the delaminated nanocomposite in toluene. FIG. 5illustrates the swelling due to toluene in a silicone compositioncontaining the stated volume fractions of the mica-type layeredsilicate. Since the ordinate axis represents the ratio of volume swellof silicone with mica-type layered silicate added to the volume swell ofthe silicone with no mica-type silicate added, there are no units and1.0 represents the volume swell with no mica-type layered silicateadded.

[0087] The phase change ink imaging member may then be prepared byapplying the elastomer having the mica-type layered silicate and anyfiller dispersed therein, directly to a substrate in one application orby successively applying layers of the elastomer composition to thesubstrate. The coating is most conveniently carried out by spraying ordipping in a light solution of homogeneous suspension containing themica-type layered silicate. Molding, extruding and wrapping are alsoalternative techniques, which may be used to make the phase change inkimaging member.

[0088] The mica-type layered silicate may be present in thepolydimethylsiloxane polymer in an amount ranging, for example, fromabout 1 to about 50, or from about 5 to about 20, or preferred of fromabout 5 to about 10 percent by weight, based on the weight of thepolymer.

[0089] The hardness of the mica-type silicate material layer istypically from about 10 to about 70 Shore A, or from about 35 to about60 Shore A.

[0090] In embodiments, the thickness of the outer mica-type silicateimaging layer is from about 0.5 to about 20 mils, or from about 0.5 toabout 6 mils, or from about 1 to about 4 mils.

[0091] The substrate, optional intermediate layer, and/or outer layer,in embodiments, may comprise fillers dispersed therein. These fillerscan have the ability to increase the material hardness or modulus intothe desired range.

[0092] Examples of fillers include fillers such as metals, metal oxides,doped metal oxides, carbon blacks, ceramics, polymers, and the like, andmixtures thereof. Examples of suitable metal oxide fillers includetitanium dioxide, tin (II) oxide, aluminum oxide, indium-tin oxide,magnesium oxide, copper oxide, iron oxide, silica or silicon oxide, andthe like, and mixtures thereof. Examples of carbon fillers includecarbon black (such as N-990 thermal black, N330 and N110 carbon blacks,and the like), graphite, fluorinated carbon (such as ACCUFLUOR® orCARBOFLUOR®), and the like, and mixtures thereof. Examples of ceramicsinclude silicates such as zirconium silicate, boron nitride, aluminumnitride, and the like, and mixtures thereof. Examples of polymer fillersinclude polytetrafluoroethylene powder, polypyrrole, polyacrylonitrile(for example, pyrolyzed polyacrylonitrile), polyaniline, polythiophenes,and the like, and mixtures thereof. The optional filler is present inthe substrate, optional intermediate layer, and/or outer layer in anamount of from about 0 to about 30 percent, or from about 1 to about 20percent, or from about 1 to about 5 percent by weight of total solids inthe layer.

[0093] The imaging substrate can comprise any material having suitablestrength for use as an imaging member substrate. Examples of suitablematerials for the substrate include metals, fiberglass composites,rubbers, and fabrics. Examples of metals include steel, aluminum,nickel, and their alloys, and like metals, and alloys of like metals.The thickness of the substrate can be set appropriate to the type ofimaging member employed. In embodiments wherein the substrate is a belt,film, sheet or the like, the thickness can be from about 0.5 to about500 mils, or from about 1 to about 250 mils. In embodiments wherein thesubstrate is in the form of a drum, the thickness can be from about{fraction (1/32)} to about 1 inch, or from about {fraction (1/16)} toabout {fraction (5/8)} inch.

[0094] Examples of suitable imaging substrates include a sheet, a film,a web, a foil, a strip, a coil, a cylinder, a drum, an endless strip, acircular disc, a belt including an endless belt, an endless seamedflexible belt, an endless seamless flexible belt, an endless belt havinga puzzle cut seam, a weldable seam, and the like.

[0095] In an optional embodiment, an intermediate layer may bepositioned between the imaging substrate and the outer layer. Materialssuitable for use in the intermediate layer include silicone materials,elastomers such as fluoroelastomers, fluorosilicones, ethylene propylenediene rubbers, and the like, and mixtures thereof. In embodiments, theintermediate layer is conformable and is of a thickness of from about 2to about 60 mils, or from about 4 to about 25 mils.

[0096] Specific embodiments of the invention will now be described indetail. These examples are intended to be illustrative, and theinvention is not limited to the materials, conditions, or processparameters set forth in these embodiments. All parts are percentages byweight of total solids as defined above unless otherwise indicated.

EXAMPLES Example 1

[0097] Preparation of Mica-Type Layered Silicates and Silicone ElastomerNanocomposite

[0098] Two samples of mica-type layered silicate and silicone elastomerwere prepared as follows. To 100 parts of a 750 centipoise alpha,omega-dihydroxysilicone obtained from United Chemical Technologies, Inc.and designated as PS342.5, 2.5 parts of tetraethoxysilane crosslinkerobtained from Aldrich Chemical Company, and 2 parts of Tin(II)ethylhexanoate catalyst obtained from Chemat and designated as T722,were added. The three ingredients were well mixed using a micro-tipultrasound probe available from Sonics & Materials. Another sample had10 parts of montmorillonite (surface treated with an amine surfactant,dimethyl ditallow ammonium bromide) mixed into the 104.5 parts ofdihydroxysilicone-crosslinker-catalyst material via a micro-tipultrasound probe.

Example 2

[0099] Preparation of Mica-Type Layered Silicate and Silicone ElastomerNanocomposite Outer Layer

[0100] To 100 parts of a 750 centipoise alpha, omega-dihydroxysiliconeobtained from United Chemical Technologies, Inc. and designated asPS342.5, 2.5 parts of tetraethoxysilane crosslinker obtained fromAldrich Chemical Company, and 2 parts of Tin(II) ethylhexanoate catalystobtained from Chemat and designated as T722, were added. The threeingredients were well mixed using a micro-tip ultrasound probe availablefrom Sonics & Materials and montmorillonite (surface treated with anamine surfactant, dimethyl ditallow ammonium bromide) was also added andmixed into the dihydroxysilicone-crosslinker-catalyst mixture using amicro-tip ultrasound probe. The specimens were made using samplesranging from 3 to 10 weight percent of surface treated montmorillonite(3 to 10 parts per hundred of the PS342.5).

Example 3

[0101] Preparation of Mica-Type Layered Silicate and Silicone ElastomerNanocomposite on Metal Substrate

[0102] The nanocomposites prepared in accordance with Examples 1 and 2may be used as a layer for a phase change ink imaging component used inink jet printing machines. A component having the nanocomposite preparedin accordance with Examples 1 and 2 may be applied directly to a basemember or substrate in one application or by successively applyinglayers of the nanocomposite to the base member. The coating of thenanocomposite compositions is most conveniently carried out byconventional coating methods, such as flow coating, slot spraying ordipping.

[0103] To 100 parts of a 750 centipoise alpha, omega-dihydroxysiliconeobtained from United Chemical Technologies, Inc. and designated asPS342.5, 2.5 parts of tetraethoxysilane crosslinker obtained fromAldrich Chemical Company and 2 parts of Tin(II) ethylhexanoate catalystobtained from Chemat and designated as T722, were added. The above threeingredients along with 10 parts of montmorillonite (surface treated withan amine surfactant, dimethyl ditallow ammonium bromide) were mixed asdescribed in the Examples 1 and 2.

[0104] This dispersion can then be coated onto an aluminum drumapproximately 100 mm in diameter. Prior to coating the aluminum drum issanded and degreased with MEK solvent, dried and primed with a silane ortitanate-based primer using known methods such as flow coating, spraycoating, dip coating, gravure coating, roll coating, and the like. Theresulting drum is then dried and step cured. After coating, the roll canbe dried and cured at ambient temperature for 12 hours.

[0105] While the invention has been described in detail with referenceto specific and preferred embodiments, it will be appreciated thatvarious modifications and variations will be apparent to the artisan.All such modifications and embodiments as may readily occur to oneskilled in the art are intended to be within the scope of the appendedclaims.

We claim:
 1. An offset printing apparatus for transferring a phasechange ink onto a print medium comprising: a) a phase change inkcomponent for applying a phase change ink in a phase change ink image;b) an imaging member for accepting said phase change ink image from saidphase change ink component, and transferring the phase change ink imagefrom said imaging member to said print medium, the imaging membercomprising: i) an imaging substrate, and thereover ii) an outer coatingcomprising a mica-type silicate material.
 2. The offset printingapparatus of claim 1, wherein said mica-type silicate material comprisesa mica-type layered silicate and a silicone elastomer, said siliconeelastomer and said mica-type layered silicate together forming adelaminated nanocomposite.
 3. The offset printing apparatus of claim 1,wherein said mica-type silicate has a general formula:W₂(X,Y)₄₋₆Z₈O₂₀(OH,F)₄ where W is potassium; X is selected from thegroup consisting of aluminum, magnesium, iron and lithium; Y is selectedfrom the group consisting of aluminum, magnesium, iron or lithium; and Zis selected from the group consisting of silicon, aluminum and mixturesthereof.
 4. The offset printing apparatus of claim 3, wherein saidmica-type silicate is selected from the group consisting of muscovite,phlogopite, biotite, lepidolite, montmorillonite, bentonite, hectorite,vermiculite and saponite.
 5. The offset printing apparatus of claim 2,wherein said mica-type layered silicate is present in the outer coatinglayer in an amount of from about 1 to about 50 weight percent based onthe weight of the silicone elastomer.
 6. The offset printing apparatusof claim 5, wherein said mica-type layered silicate is present in theouter coating layer in an amount of from about 5 to about 20 weightpercent based on the weight of the silicone elastomer.
 7. The offsetprinting apparatus of claim 2, wherein said silicone elastomer is apolyorganosiloxane.
 8. The offset printing apparatus of claim 7, whereinsaid polyorganosiloxane has the following formula:

 wherein R is selected from the group consisting of hydrogen, alkyl,alkoxy, alkenyl, and aryl; A is selected from the group consisting ofalkyl, alkoxy, hydroxy and vinyl; B is selected from the groupconsisting of alkyl, alkoxy, hydroxy and vinyl; and 0<m/n<about 1, andm+n>about
 350. 9. The offset printing apparatus of claim 8, wherein Aand B are vinyl.
 10. The offset printing apparatus of claim 7, whereinsaid polyorganosiloxane is a silanol-terminated polydimethylsiloxanehaving the following formula:

where n′ is an integer of from about 350 to about 2,700.
 11. The imageforming apparatus of claim 7, wherein said polyorganosiloxane is anaddition-cured polyorganosiloxane having the following formula:

wherein s and r are integers and 0<s/r<1; A″ is selected from the groupconsisting of hydroxy, alkoxy, hydride, vinyl, and amine; B″ is selectedfrom the group consisting of hydroxy, alkoxy, hydride, vinyl, and amine;and R″ is selected from the group consisting of alkyl, phenyl, andvinyl.
 12. The offset printing apparatus of claim 1, wherein anintermediate layer is positioned between said substrate and said outercoating.
 13. The offset printing apparatus of claim 12, wherein saidintermediate layer comprises a material selected from the groupconsisting of elastomers and silicone materials.
 14. The offset printingapparatus of claim 1, wherein said outer layer comprises a filler. 15.The offset printing apparatus of claim 14, wherein said filler isselected from the group consisting of carbon blacks, metal oxides,metals, polymers, ceramics, and mixtures thereof.
 16. The offsetprinting apparatus of claim 1, wherein said phase change ink is solid atabout 25° C.
 17. The offset printing apparatus of claim 1, wherein saidphase change ink comprises a dye.
 18. An offset printing apparatus forprinting a phase change ink onto a print medium comprising: a) a phasechange ink component for applying a phase change ink in a phase changeink image; b) an imaging member for accepting said phase change inkimage from said phase change ink component, and transferring the phasechange ink image from said imaging member to said print medium and forfixing the phase change ink image to said print medium, the imagingmember comprising in order: i) an imaging substrate, ii) an intermediatelayer, and iii) an outer coating comprising a mica-type silicatematerial; and c) a heating member associated with the offset printingapparatus.
 19. An offset printing apparatus comprising: a) a phasechange ink component containing a phase change ink; b) a imaging membercomprising: i) a substrate, and thereover ii) an outer coatingcomprising a mica-type silicate material; and c) a heating memberassociated with said offset printing apparatus, wherein said phasechange ink component dispenses said phase change ink onto said imagingmember, and wherein said phase change ink is solid at about 25° C.